Sutra 3.31

कूर्मनाड्यां स्थैर्यम्॥३१॥

kūrma-nāḍyāṁ sthairyam ॥31॥

kUrma=tortoise; naaDyaaM=on the subtle channel (nadi); sthairyam=steadiness

Sw. Satchidananda

By samyama on the kurma nadi (a subtle tortoise-shaped tube located below the throat), motionless in the meditative posture is achieved.

Bryant

[By samyama] on the subtle tortoise channel, steadiness is attained.

Taimni

(By performing Samyama) on the Kurma-nadi steadiness.

Aranya

Calmness Is Attained By Samyama On The Bronchial Tube.